MBSA 2.0.1 is an update to MBSA 2.0 to enable compatibility with the new Windows Update (WU) offline scan file. MBSA version 2.0.1 does not contain any new features but simply enables MBSA to download and read the new file format.
In order to run offline scans, MBSA 2.0 must have the scan file on the scanning machine. MBSA 2.0 automatically downloads this file if the scanning machine has Internet access. If not, the file must be downloaded and installed manually. MBSA 2.0.1 behaves in the same manner, except that it uses the new scan file.
If you use MBSA in the offline mode, you will need to download the new version of MBSA. You will also need to download the new offline scan file, wsusscn2.cab. Download details are discussed on this page: http://www.microsoft.com/technet/security/tools/mbsa2/default.mspx.
For more information check out the links below: